I. Boscolo, F. Castelli, S. Cialdi, D. Cipriani

CARE-PHIN FP6at Milano

CARE-PHIN-December 2008

Summary from Lecce PHIN Collaboration meeting

The taskTitle of Milano - JRA2 - CARE scientific task:

Two technologies

• LCM-SLM (liquid crystal mask – spatial light modulator)

• Dazzler-AOPDF (acousto optic programmable dispersive filter)

“Investigate and test systems for complicated ultra-fast optical waveforms according to user specifications, as those for the new generation of FEL, with benefits for linac photo-injectors.”

the achievements Studied and developed the 4f-system and implemented in the SPARC machine at Frascati

Studied and tested the DAZZLER in

FrascatiProposed and successfully tested a novel optical system as pulse shaper for rectangular UV laser pulses.

A pulse train generationSome work on CLIC Phase-Coding system + a PHD collaboration Malka

The 4f-system LCM-SLM

1. Developed in Milano Lab a Nd;YAG laser system for studing and testing

2. Studied and set the 4f-system driven by an adaptive algorithm

3. Studied and solved the general pulse shaping problem with harmonic generation, tetsted in SPARC machine

shapingncompressiomask

UV pulse in SPARC with DAZZLER 2.6 ps rise time 6 ps wide

The final result resulted un-satisfactory: too long rise time

New idea:

A new design stretcher at the UV

New 4f-shaping scheme

222

3

sin1

1

io

o

d

dc

h

h

mask

From thesis of Valeria Brizzolara

Entering pulse Output pulse

[ps] [ps]

Autocorrelator

Stretcher-compressorScheme of the experimental setup

Extention for SPARC

h

UV pulse

Tool to reduce the rise time of the UV rectangular pulse

Simulation

Iris

Pulse output with the new stretcher after UV-HG 1.4 rise time

Published articles about laser pulse shaping

• 9 papers

• Conferences proceeedings

• 5 Physics thesis (MI)

Phase Coding system tests in Milano

Operation of the Phase Coding System

Re-pattern a CW 1.5 GHz mode-locked laser beam into a laser beam made up of a succession of trains as shown in figure;

1. fiber launch losses

2.Modulator losses

3.Fiber-fiber junction losses

4.Fiber beam-splitter losses

5.Entire system losses

6.RF-driver modulus test

7.Full system operation

THE EXPERIMENTAL TESTS IN MILANO

1- Fiber launch losses

input and output collimators are lossy about 15 %.

Losses 1 dB

Choose collimators tailored to our wavelength

2- Modulator losses Pin mW Pout mW e

%

75 15 20

170 30 18

250 45 18About 2 times higher than CCLRC estimate

3-Fiber-fiber junction losses loss of about 0.5 dB

Junction soldered

4- fiber beam splitter losses

Again higher than foreseen

Measured: Pout about 7 mWVery difficult to set correctly fiber junctions and input fiber launch

measurementsPin 300 mW expected Pout 10.7 mW

5 F U L L S Y STEM LOSSES

6- test of RF-driver amplifier

The item is now fixed

Trains of the right length are generated

7- full system operation

The interleaving is tested positively

Power test of full system

Pin = 300 mW

Pout = 2 mW measured

Assuming the best launch and junctions

Pout expected 0.017x300 = 5.2 mW

System with soldered junctions and tailored collimators Pout expected 0.045x320= 14.4 mW

Unless we can find a better performace with the modulator